Coagulase-negative staphylococci, with the leading species Staphylococcus epidermidis (S. epidermidis), have over the past decade become the most prevalent pathogens involved in hospital-acquired infections (Vuong, C., and Otto, M. Microbes Infect. 4: 481-489, 2002). For example, in the United States alone, S. epidermidis infections on in-dwelling medical devices cost the public health system approximately one billion dollars per year (Vuong, C., and Otto, M. Microbes Infect. 4: 481-489, 2002).
S. epidermidis is usually an innocuous commensal microorganism on human skin. This microorganism can cause severe infection after penetration of the epidermal protective barriers of the human body. To survive on the human skin and during infection of in-dwelling medical devices, S. epidermidis circumvents human innate host defenses (Hornef, M. W., Wick, M. J., Rhen, M., and Normark, S. Nat. Immunol. 3: 1033-1040, 2002). For example, S. epidermidis is frequently resistant to common antibiotics (Vuong, C., and Otto, M. Microbes Infect. 4:481-489, 2002). The formation of surface-attached cellular agglomerations known as biofilms is believed to contribute significantly to antibiotic resistance and protection of the organism from innate host defense (Costerton, J. W., Steward, P. S., and Greenberg, E. P. Science. 284: 1318-1322, 1999). Further, it has been suggested that resistance of S. epidermidis biofilms to some antibiotics is in part due to a status of generally reduced metabolism (Yao, Y., Sturdevant, D. E., and Otto, M. J. Infect. Dis. 191: 289-298, 2005). Thus, S. epidermidis is one of the difficult hard-to-treat infectious agents that can be transmitted nosocomially to patients in hospitals, especially such patients who have in-dwelling medical implants.
It would be advantageous to provide compositions and methods of treating staphylococcal infections, such as coagulase-negative staphylococcal infections, for example S. epidermidis infections.